From 19e2a9fb9da067acba95b3be83588bda5a3f6a99 Mon Sep 17 00:00:00 2001 From: Zeng Guang Date: Thu, 25 Aug 2022 10:52:46 +0800 Subject: [PATCH] target/i386: Set maximum APIC ID to KVM prior to vCPU creation Specify maximum possible APIC ID assigned for current VM session to KVM prior to the creation of vCPUs. By this setting, KVM can set up VM-scoped data structure indexed by the APIC ID, e.g. Posted-Interrupt Descriptor pointer table to support Intel IPI virtualization, with the most optimal memory footprint. It can be achieved by calling KVM_ENABLE_CAP for KVM_CAP_MAX_VCPU_ID capability once KVM has enabled it. Ignoring the return error if KVM doesn't support this capability yet. Signed-off-by: Zeng Guang Acked-by: Peter Xu Acked-by: Michael S. Tsirkin Message-Id: <20220825025246.26618-1-guang.zeng@intel.com> Signed-off-by: Paolo Bonzini --- hw/i386/x86.c | 4 ++++ target/i386/kvm/kvm-stub.c | 5 +++++ target/i386/kvm/kvm.c | 5 +++++ target/i386/kvm/kvm_i386.h | 2 ++ 4 files changed, 16 insertions(+) diff --git a/hw/i386/x86.c b/hw/i386/x86.c index bd50a064a3..78cc131926 100644 --- a/hw/i386/x86.c +++ b/hw/i386/x86.c @@ -140,6 +140,10 @@ void x86_cpus_init(X86MachineState *x86ms, int default_cpu_version) exit(EXIT_FAILURE); } + if (kvm_enabled()) { + kvm_set_max_apic_id(x86ms->apic_id_limit); + } + possible_cpus = mc->possible_cpu_arch_ids(ms); for (i = 0; i < ms->smp.cpus; i++) { x86_cpu_new(x86ms, possible_cpus->cpus[i].arch_id, &error_fatal); diff --git a/target/i386/kvm/kvm-stub.c b/target/i386/kvm/kvm-stub.c index f6e7e4466e..e052f1c7b0 100644 --- a/target/i386/kvm/kvm-stub.c +++ b/target/i386/kvm/kvm-stub.c @@ -44,3 +44,8 @@ bool kvm_hyperv_expand_features(X86CPU *cpu, Error **errp) { abort(); } + +void kvm_set_max_apic_id(uint32_t max_apic_id) +{ + return; +} diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c index 4df0428089..a213209379 100644 --- a/target/i386/kvm/kvm.c +++ b/target/i386/kvm/kvm.c @@ -5723,3 +5723,8 @@ void kvm_arch_accel_class_init(ObjectClass *oc) "Clock cycles without an event window " "after which a notification VM exit occurs"); } + +void kvm_set_max_apic_id(uint32_t max_apic_id) +{ + kvm_vm_enable_cap(kvm_state, KVM_CAP_MAX_VCPU_ID, 0, max_apic_id); +} diff --git a/target/i386/kvm/kvm_i386.h b/target/i386/kvm/kvm_i386.h index b7c38ba2c4..6a5c24e3dc 100644 --- a/target/i386/kvm/kvm_i386.h +++ b/target/i386/kvm/kvm_i386.h @@ -66,4 +66,6 @@ typedef struct kvm_msr_handlers { bool kvm_filter_msr(KVMState *s, uint32_t msr, QEMURDMSRHandler *rdmsr, QEMUWRMSRHandler *wrmsr); +void kvm_set_max_apic_id(uint32_t max_apic_id); + #endif -- 2.11.0